A seat is installed at the inside of the vehicle so that an occupant can be seated on the seat, which is composed of a seat cushion that supports the gluteal region of the occupant, a seat back that supports the back region of the occupant, armrests that enables the occupant's arms to put thereon, and a headrest that supports the head of the occupant.
Among these elements, the seat back associated with the present invention will be discussed hereinafter in detail. A seat back frame is installed at the inside of the seat back so as to serve as a framework of the seat back, and a lumbar support assembly is installed at the inside of the seat back frame so as to support the back region of the occupant.
The lumbar support assembly has a variable structure that can fit the spinal shape of the occupant in order to reduce the fatigue of the occupant during the driving of the vehicle.
The lumbar support assembly will be described hereinafter. A protrusion is formed on a rotary bar that is rotatably coupled to the seat back frame, and then a support member is installed on the protrusion to support the lumbar region of the occupant so that the rotary bar is rotated to cause the support member to be moved in the forward and backward directions of the seat back frame depending on the posture of the occupant who is seated on the seat so as to support the lumbar region of the occupant.
However, this conventional lumbar support assembly entails a problem in that it is assembled and manufactured by a number of parts, thus leading in increases in the failure rate and the manufacturing cost and time, and in that vibration and shock generated depending on road or traffic conditions during the driving of the vehicle are transferred to the lumbar region of the occupant through the protrusion to make the occupant feel fatigue easily or cause a risk of injury to him or her.